commie wrote:
Why don't the black boxes float? wouldn't that make it easier to get to them in the event of a water crash?

The boxes are installed in the tail of the aircraft, so a floating box would only really work as designed if the boxes get separated from their mountings in the tail.  It's fairly rare for the boxes to be thrown completely free from the tail structure, so it's not cost effective or design effective to require floating boxes.  It's possible to do it as a technical matter (the Cessnas I fly have floating emergency locator beacons), it's just not seen as necessary.

Because of this crash various people have also called for aircraft to be equipped with black boxes that datalink via satellite to provide real time downloads of the box data to a ground station.  Again, technically possible but in practice not really feasible given the sheer volume of data.
  

"C'mon Reg, how many times do I have to remind you? Be conservative, not retarded." - (c) Rusty Iron Ring 2011